Optical unit and method of projecting images to obtain stereoscopic relief



Pateixted Feb. 1932 (UNITED STATES PATENT OFFICE zm1srmx. mxs cn'namn, o1r CHICAGO, mnnmxs orzncu. um um mixen oir riazomcmnwq num1:s mo o1 snm suinnnosoonc manmr Appli catio n und September 25, was. symiu 1m. 1s7,e51.

This invention relates to an optical mit for forming dual colored images und to a. method of projgcting images to obtain stereoscopic reliief.

It has heretoforebeen found pqssible to obtainstereosgopic relief in pToj ectiad images only by elaborate und impracticable methods.

j One such method as applied to movin pictures consists in takin .the picture in upli- 1 cate so as.to form over apping objects on the eflect, the right und left outl1ne of each obj ect on the film niust be criefully traced in colors that am substa ntiallycom lementary to euch zu other. This operation, in he case moving picture fil ms, is necessarily laborious and expensiv e und. diflicult to accomplish with any degree ofthoroughne'ss.

I t is 'therefore an object O'f this invention to provide a suitable optica'l unit and method for accomplishing in a simple "fashion the desired-stereoscopw relief in projected images, using the ordinafy single exposed bla'ck und whit'e film, 01 plate. 4

Itis a. further object of this invention to provide an optical uxiit that'may be used for vvariouspur'poses but more especially in counection with ordinary projecting lanterns to p' rodude a dual colored projected image, which when v icwed through 'colored .spectacles will stand outin5tereoscopic relief.

Other und further important objects of this invention Will be apparent from the disclosures in the specification und the accompanying dmwins. 3

This invention (in a prefer'red fo'rm) is illustrated in the drawings 'an d hereinafter more fully describe'd.

On the dra wings:

Figure 1 is a rear elev ational view 0f an optical unit embodying the prin'ciples cf my invention in a preferred form.

Figure2is a top lan edge view 01 the same. Figure 3 is an elevational end view of the same.

- invention.

und thc thinner Ezdges 10 and Figure 4 is a 'rear elevational view of a. modified form of my invention..

Figure 5 is an iend elevational edge view of Fi ure 4. H

igure 6 is a second: modified form of my Figure 7 is a third modified form of my invention.

F i re 8 is a diagmmmatic view illustrating t e modus 0 erandi. a,

As shown on t e rawings:

In Figures 1' to 3 inclusive, refenence numeral 1 indicates a sphero-prismatic optical 1init comprising a plurality .of prisms 2, 3, 4 und 5, formed in the present instance in quarterseetors und suitably secured to the rear plane face 6 of a plane conye'x lei1s 7. Said prisms 2, 3, 4an'd 5 alxe each formed in the shape of a Wedge, with one edge thicker than the' ofiher. In accordance with the principles of my inventio'n a s will later be ex- Plained, the wedge shaped prism 2 is pos'i'- tibned with the base 8 ahutting the base 9 of the prism 3. In the case o f the pr'isms 4 und 5, however th6 osition is reversed.

11 respectively lie in abutting relation.

' In carrying out my inventidn as it relates to the projection of moving pictures, the

prisms 2 and 4 are preferably' ground from so green glass aLnd the prisms 3 und 5 fro'm redglass.-- In any case the colors chosem should be substantially complementary to each other und dia' onally Oppositeprisms ofthe same 00101. he same eflect may also be prodlic'ed by either cdvering the faces of the prisms 3 and 4 with separately colored sh(aets of transparent material or by inserting such material between the prisms and the Inne surface 6 of the spherical lens 7 Co ored celluloid 01 cellophane may be used.

Th e sphero-prismatic optical unit such as above described may be used'with an ordinary projecting machine for moving pictures .to obtain a stereoscopic efli'ect. The film used is the ordinary single expos ed blat:k and white type. Thelig'ht from the objects on the film will be colored in passi'ng through the respective prisms und will also -be refracted accord ing t0 the known law of prismsJ will be projected in passing through the ward direction. If the degree 0fthe prisms is suitably chosen, one-half a degree being found satisfactory, the objccts on fhe film optical unit as two imags 0n t-l1e screen, these images lying in overlapping relation. Th1's will be apparent from the following explanation. Bach of the prisms 2, 3, 4 and 5 in connection with the convergent lens 7 in eifect servesto throw a complete image 0f the object 011 the screem, but since tl1e prisms 2 and 4 euch refract the rays 0f light from the object in the san1e direction, namely toward the 1ight, the i1nages f0rmed by these prisms in connection With the c0i1vergent efl'ect 0f the spherical lens 7 will be clisplacecl t0 the right one-half a degre0 each and the two green images Will thereby b.e perfectly superin1posed. Similarly, light passing through the prisms 3 and 5 is coloredred and is refracted toward the left one-half a degree and the two red images thereby perfectly superimposed one over the other. There will thus be formed on the screen dual overlapping images having right and left outlines in pomplementary colors. 'It Will be' appreciated that the overlapping portion 0f the images Will be a neutral 00101 due to the neutralizing efi'ect 0f the.-complementary colors red and green. Where the light is projected through blank .p0ttions of the film, the 00101 produced on the screen by the blending of the co1nplenlent-ary colors will be a creamy whlte.

The stereoscopic effect'is produced upon anyone Who views the dual image thrown on the screen through spectacles, the eye pieces of Which are complementarily colored transparent material. This result follows from Well known principles and d0es not 0f it self form a part of my invention, which resides rather in the construction of an optical unit to produce the colored dual image eilect on the screen. In ger'1eral this eflect is due to the use of light divergent means in combination with means :Eor coloring the rays in complementary colors and other means f01 converging the rays t0 form distin'ct Superimposed images.

fied optical structure for obtaining the same result. Said structure comprises a pair of semi-circular prisms 12 and 13 having red and green colored transparent films 14 and 15 respectively secured to the surfaces thereof. Said prisms 12 and 13 are joined along their inner edges 16 and 17 respectively with their bases extending outwardly. A. -plano convex lens 18 is suitably cemen ted t0 said prisrns 12 and 13 with plane surfaces abutting.

The path of light fr0m an object 19 in passing through the optical unit shown in Figures 4 and 5 is diagrammatically illustrated in Figure 8. F 01 instance, a beam of light represented by the dotted line 20 paSsing through the head of the arroyv 19 representing an object 011 the film and substantially parallel to the axis 0f the lens 18 Will be deflectecl 011 entering the prism 12- in the direction indic abecl by the divergent line 21. This Same beam 0f light will be refracted again toward the axis by the spherical lens 18 and take a path indicated by the line 21 In passing through the prism 12 the beam 20 Will be colored red and be projected as a recl beam 0f light along the path 21. Similarlya bea m of light 22 from the other end of the object 19 Will be outwardly refracted as at 23 in passing through .the prism 13 and Will be converged as beam 24 by the lens 18. If now lines 25 and 26 be drawn from the opposite ends of the 0bject 19 to represent beams 0f light passing substantially through the focal center of the lens 18, the images formed may be represencecl on a screen 27 by the dotted line 28 and full line 29, shown for the sake of clear ness in ofl'set position from the line 27 representing the scree1n It Will be apparent that these images 28 and 29 will be formed in overlapping position and that the nonoverlapping portions 013 each image will appear colored t0 correspond with the color of 1 ehe prism through which the beam 0f light has passed. F01 instance, one and of the image 29 represented by the arr0w head 30 will be gr0en, whereas the other end 015 the image 28 represerited by the arrow tail 31 will be red. The effect of viewing an everlapping dual colored image such as described tl 1rou'gh similarly colored spectacles is to g1ve depth to the picture, similar t0 that obtained by viewing dual pictures through a stereoscope.

At this point it might be well t0 explain that; with' either 0f the optical units above discussed, better results are obtained if a minus lens 42 (Figure 8) is interposed between the optical unit and the screen, pref erably byond the focal points. The eifect 0f the minus lens is, 'of course, t0 enlarge the image, but it seems also to render the In Figures 6 and 7 there are shown mqdified forms of optical units that may be substitutecl fo1 t-he forme: already described, although in general with lass satisfactoryreimages 0n the screen more animate and life- 1 In F1gures 4 and 5 there is shown a 1n0d1- l'k sults. In Figure 6 there is shown a plano convex lens 32 tp the, plane side of which a re aflixed plane concave lenses 33 and 34. Color screens 35 und. 36 are used in connection with the plane concave lenses 33 and 34 respectively in a similar way t that already. described. It will be apparent that the minus lenses 33 and 34 will serve to diverge the rays of li ht and in this way will fo'rm dual images w 'en used in connection with a converging lens 32.

In F igure 7 therg is shown a pair of plano convex lenses 37 and 38 of semi-circular form and joined at their Common chord 39. Said lenses 37 and 38 are preferably formed from a single circular lens by dividing said lens in halves and gri'nding away a portion of auch 0f the newly formed edges. If now the halves 37 and 38 are jqined along said edges 39, the optic'al unit formed Will have a divergent efi'ect due t0 the fact that the curved face is no longer 0f uniform curvature throughout. Colored screens 40 and 41 may be cexnented t0 the plane surface of said lenses 37 and 38 t0 get the desired color eifect. Instead of grinding away the edges along the diamters of the lenses 37 and'38, said lenses may be separated b an opaque strip and a similar divergent e ecl; obtained.-

The optical units as above describdd may be used in connection with moving picture projectors using the ordinary black and white film and wit-hout any other change .than the ubstitution of lenses. The efl'ect is to throw all ofthe objects on the screen', including the background, into stereoscopic relief. This is accentuatedby the black frame snrrounding the pict-ure. Formerly, when the films were color'ed with complementary 'colors, it was impossible to get this same qflect, since obviously the background could not be colored with the minutenessnecessa to make it stand out in stereoscnpic rel1ef. Accoidingly the background would appean to vibrate due to the optical efl'ect.

It will be app'arent that the optical unit-s described may be used for other 'purposes than in movi ng picture projectors. F01 instance,- an optical unit emb0dying the printography for taking dual images. In that ciples of my invention may be used in phound a projecting screen, comprising in succ ession light iverging pnsms arranged about a common axis for dividing the light from the film into a plurality of complete images, a convergin lens having a comvergent power so re ated to the divergent power of the prisms, and so Positioned with respe'ct to said prisms and said screen as to form overlup ping images on the screen und means for coloring the images in substantially complementary colors, whreby dual overlatpping Images are formed on the- *screen which when viewed through eyeprisms, and so positioned with respect to said.

prismsand said screen asto form overlapp1ng 1mages on the screen, and a concave lens, the dwergent power of wh1ch 1s less than the convergent power of said convergent lens, whereby a real image Will be produced, and means for coloring the images in substantially complementary colors, whereby dual overlaping images are formed on the creen, and when viewed through eye-p1eces of the same colors as the projected images, give a stereoscopic illnsion.

In testimony whereof I have hereunto subscribed my name.

NATHANIEL BANKS GREGIER.

case, howevr, the color screens could be omitted.

I am aware that many changes may be made, and numerous details of ponstri1ction may be varied through a wide range without departing from the principles of, this inven tion and I therefore do not purpose limiting the patent ranted hereon, otherwise than necessitate by the prior airt.

I claim as my invention:

unit for use with an illuminated single exposure fi1m of the black und white type 

